38 RUDOLF SÖDERBERG, STUDIES OF THE BIRDS IN NORTH WEST AUSTRALIA. 
The colour of the eggs varied a little. On a yellowish or bluish-yellow ground 
there were bigger or smaller red-brown spots close together over all the surface of 
the egg. As to the variation, this was considerably less than the case is with the 
eggs of our general Sterna hirundo L., to which they can be compared only as far 
as form and size is concerned. I have made very minute examinations of the colour 
of these eggs (published in my article on »Hornborgasjöns fågelliv», Arkiv för zoologi, 
Band 1, 1907). The two basic colours that these eggs show viz. dark brown and 
light grey seem to be due to the fact that the tern lays its eggs in a brown moss 
or in a light blue lichen, plants which compose the vegetation on those small cliffs, 
where it breeds. 
It was therefore of great interest to me — and I must add that the reason I 
visited those inaccessible rocks was because of my wish to examine this case — to 
find the eggs of Sterna ancestheta in its red-brown ornamentation corresponding to 
the red sandstone on which they were lying. (In most of the nests there was only 
one egg, but in some of them there were three, without doubt laid by different birds). 
Here I may also mention, that once, when I was in Geraldton, a town in the 
South part of West Australia, I had an opportunity of seeing some tern-eggs taken 
from sandbanks at Alboroh Islands. I do not know the species, but I am convinced 
that this tern breeds on sandy islands, sand-banks or such places. For these eggs 
had a veritable sandy-colour (sandy buff or pale buff basic colour) and were sprinkled 
with black points, in colour and ornamentation like the eggs of Aegialites hiaticula (L.) 
which are the best sandy-coloured eggs to be found. 
A comparison between eggs of all species of terns and their respective dwelling- 
places from the point of view of the colours would, I am certain, give many proofs 
of analogies and show interesting contrasts and convergences between the species due 
to their breeding-localities. The species Hydrochelidon nigra (L.), which is rare in 
Sweden, has, for instance, very dark-spotted eggs, reminding one very much of these 
of certain waders, and it breeds too at similar places to those birds (in marshy 
districts). And it is the same with other species of terns in other parts of the world, 
whose eggs I have had an opportunity of seeing. 
I was surprised to see brooding birds able to endure the great heat of the 
sun shining here on the stone ground, and I saw dark nestlings lying gasping in 
the sun. Those who could, preferred to seek a shady place. There were thousands 
of terns breeding here. The rocks looked like a miniature hill of birds. 
Larus nov&-hollandig& STEPH. 
Math. handl. n:r 137. J ad. Freemantle ?5/9 1910; 2 29 juv., ad. Broome, Damp. land ?2/& 1911; 
1 P2 ad. Beagle bay, Damp. land 21/7 1911; 2 SS juv. ibid. 2/7, 21/7 1911; 5 29 juv. ibid. 8/1, 2/7, ?/e, 
"Brr and 
Plumage. — The young specimens have greyish brown feathers in the wings. 
The colour of their eyes is dark-brown whereas the adults have the iris whitish yellow. 
Bill blackish, legs grey-brown (those of the adults coral-red). In one of the adults, 
